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- IPsec Tunnel not Establishing
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Overview
This article outlines how a service provider is leveraging AmZetta zWAN to enhance VoIP traffic performance across distributed customer environments.
The deployment focuses on packet-based routing, bidirectional QoS, DSCP marking, and monitoring voice quality metrics to ensure reliable, high-quality voice communications.
Environment Details
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Component
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Description
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zWAN Hardware
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z40 Gateway Router deployed at remote site
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zWAN Virtual Appliances
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vGR hosted in cloud DC
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Management
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Centralized zWAN Director
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VoIP Test Device
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Laptop on LAN side of z40
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Connectivity
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IPsec tunnels between z40 and vGR/Director
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Architecture Diagram (High-Level Topology)
How zWAN Enhances VoIP Performance
1. Packet-Based Routing for Voice Media
The provider required packet-level processing rather than session-based flow handling to ensure:
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Lower latency
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Stable jitter characteristics
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Consistent voice quality during high-load situations
zWAN handles packet-based routing by default for tunneled traffic, making it ideal for VoIP workloads.
2. Bidirectional QoS for Audio, Video & Sharing Traffic
The deployment required priority control for:
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Audio (highest priority)
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Video
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Application sharing
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Background/default traffic
Bidirectional QoS Workflow Diagram
Priority classification was performed using:
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DSCP marks
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IP ranges of VoIP services
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UDP port ranges (audio, video, screen sharing)
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Optional DPI (Deep Packet Inspection)
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Source/destination subnets for inbound QoS
This ensured audio streams were protected in both directions, which is critical for stable VoIP.
3. DSCP Marking & Verification
The provider validated DSCP handling using:
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Wireshark packet captures
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tcpdump on both z40 and vGR
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CLI scripts for QoS class and queue visibility
Example DSCP validation command:
tcpdump -vn -i IPSEC004. Monitoring Voice Quality Metrics
The provider used zWAN TWAMP to track:
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Round-trip time
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Latency
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Packet loss
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Jitter
These metrics were used to validate real-time call quality under different bandwidth and failover conditions.
5. Automatic WAN Failover
Voice sessions continued seamlessly during WAN link interruptions, thanks to:
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Per-interface QoS
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Automatic tunnel re-establishment
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SIM backup interface support
This ensured uninterrupted VoIP during outages or poor network conditions.
Benefits of Using zWAN for VoIP
✔ Superior Voice Quality
Priority queues ensure voice packets are processed first, minimizing jitter and delay.
✔ End-to-End DSCP Integrity
Markings set at the client or at either zWAN endpoint are preserved across tunnels.
✔ Bidirectional QoS (Unique vs. Many SD-WAN Solutions)
Both outbound and inbound VoIP traffic receives correct classification and guaranteed bandwidth.
✔ Detailed Real-Time Visibility
Admins gain insight into:
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Queue usage
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DSCP values
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Per-class bandwidth
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Media flow behavior
✔ High Availability for Voice
Fast, stable WAN failover protects live voice calls.
Conclusion
This deployment demonstrates how a service provider successfully optimized VoIP performance using AmZetta zWAN. With packet-based routing, enhanced QoS capabilities, detailed analytics, and reliable failover, zWAN ensures high-quality voice communication across distributed environments.
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